pH monitor vs. liquid test kits!

[cmor1701d]

Who here is using a pH monitor (Pinpoint, Milwakee, etc.) AND also compares the reading to a liquid test kit (API, Salifert, etc.)?

My PinPoint pH monitor (3 months old) always reads my tank and PWC water in the 7.6 - 7.8 range.
API shows as 8.2 - 8.4 and Salifert shows 8.2. Both liquid kits are new.

I calibrated the monitor when I got it, and at least once a month.

Today I called American Marine. Lou called me back and we discussed my calibration technique. Lou then claimed that the monitor was calibrated correctly, but liquid test have a high pH bias.

Anyone else aware of this or have this problem?
Is everyone running their tank with 5x - 10x lower pH than NSW?

 

[cmor1701d]

BTW, water params from 5/30
Temp 79
pH 7.86 or 8.2
Alk 14dKH - 5.03 meq/L
Ca 365
Mg 1500

Did another 25% PWC after those readings with another one planned this weekend.

 

[Crepe]

Hmm do you know how PH meter's work? They go by electrical resistance right? Maybe it could be the minerals in the water...making the water more conductive...although i'm probably wrong.

 

[ryshark]

I use a PH probe connected to my controller. I'm pretty sure it is accurate. Did you calibrate yours with 2-PH solutions a high solution and a low solution? I use pinpoint 7.0 and 10.0 calibration solution.
That is some high alk and mg. IMO ca on the verge of being too low. Is that what you are working on bringing down and up? What saltmix do you use?

 

[cmor1701d]

Based strictly on the 'calibrated' monitor I was trying to raise pH. That brought my alk up to riduculous levels. I was unable to do any pwc's for over a month, so I ended up doing 100% water change over a week. Still working on getting Ca up a bit. I'll start dosing again this weekend after my next pwc.

I have calibrated it 5 times in 3 months using 7.01 and 10.01 solution, following the manufacture recommendations (as noted in my original post).

Have you checked your pH with a liquid test kit to compare it to your meter?
Whose probe are you using?
Which controller are you using?
I'm thining of getting one and a dual pump for my 2-part dosing.

Thanks

 

[ccCapt]

Sorry I can't help since I haven't test my pH in probably 10 yrs. But, what salt are you using? Your parameters are all whacked out. I think every coral in my tank would be dead at that high alk.

 

[ryshark]

Based strictly on the 'calibrated' monitor I was trying to raise pH. That brought my alk up to riduculous levels. I was unable to do any pwc's for over a month, so I ended up doing 100% water change over a week. Still working on getting Ca up a bit. I'll start dosing again this weekend after my next pwc.

I have calibrated it 5 times in 3 months using 7.01 and 10.01 solution, following the manufacture recommendations (as noted in my original post).

Have you checked your pH with a liquid test kit to compare it to your meter?
Whose probe are you using?
Which controller are you using?
I'm thining of getting one and a dual pump for my 2-part dosing.

Thanks

I use the Neptune Apex, I paid a little extra for the lab grade PH probe. Here is the link http://www.reefgeek.com/equipment/C..._Lab_pH_&_Temp_Probe_&_EB8_by_Neptune_Systems

 

[cmor1701d]

Well Larry. As usual you are correct (for sps anyway).

Ryshark, would you mind picking up an API pH kit and testing it against your probe? I'm really interested to find out how much of a difference there is.

Lou from American Marine told me it the monitor is properly calibrated (and mine is) then it is correct no matter how many liquid test kits you compare it to.

I will check the calibration this weekend to make sure the unit is holding calibration. If is then I am stumped about my pH. More PWCs is about all I can do.

I'm using Red Sea Coral Pro which measures great for my PWC tank except for pH measured by the probe. The liquid test kits show it at 8.2

 

[ryshark]

Well Larry. As usual you are correct (for sps anyway).

Ryshark, would you mind picking up an API pH kit and testing it against your probe? I'm really interested to find out how much of a difference there is.

Lou from American Marine told me it the monitor is properly calibrated (and mine is) then it is correct no matter how many liquid test kits you compare it to.

I will check the calibration this weekend to make sure the unit is holding calibration. If is then I am stumped about my pH. More PWCs is about all I can do.

I'm using Red Sea Coral Pro which measures great for my PWC tank except for pH measured by the probe. The liquid test kits show it at 8.2

I may have an API PH kit around, I will see if I can find it and check the date. I kind of agree with Lou becaue you know the calibration solution is correct. If I were you I would try to get the PH up to at least a solid 7.8 other ways than just doing pwc.... I know now you have to because your parameters are all out of whack. But here is what I would do to increase PH
1. Angle powerheads up to really make the surface look like a Jacuzzi
2. Get a bigger protein skimmer which draws more air, or connect a tube going from the air intake/venturi part of the skimmer and route it outside.
3. Keep the windows and doors open to get fresh air in the house.
4. Increase light time, depending on what you are already at.

 

[cmor1701d]

Ray,

I can't increase surface agitationanymore than it is withougt blowing water out of the tank.

My PS is already oversized for my tank and draws in plenty of air.

A/C is on when it's hot, otherwise at least one window is open in the room wtih the tank.

Lights are on for 12 hours.

BTW water parameters in the tank yesterday (before today's pwc)
Temp 79
pH 8.2 (salifert) or 7.65 (probe)
Alk 12
Ca 400
Mg 1460
NO3 2.5

I am running np BioPellets which can reduce pH. That's why the trickle outflow is placed right next to the PS intake pump.

The probe reading are the same now as they were before I started using the BioPellets.

The only way to increase the pH will also blow the Alk through the roof,

My change water has the same readings. When mixed to 1.025 the liquid test kits show 8.2/8.3 while the probe shows 7.8

So if Lou is correct then everyone using a liquid test kit has a pH much lower than actual. If that is true, then is it really so bad?

 

[ryshark]

Ray,

I can't increase surface agitationanymore than it is withougt blowing water out of the tank.

My PS is already oversized for my tank and draws in plenty of air.

A/C is on when it's hot, otherwise at least one window is open in the room wtih the tank.

Lights are on for 12 hours.

BTW water parameters in the tank yesterday (before today's pwc)
Temp 79
pH 8.2 (salifert) or 7.65 (probe)
Alk 12
Ca 400
Mg 1460
NO3 2.5

I am running np BioPellets which can reduce pH. That's why the trickle outflow is placed right next to the PS intake pump.

The probe reading are the same now as they were before I started using the BioPellets.

The only way to increase the pH will also blow the Alk through the roof,

My change water has the same readings. When mixed to 1.025 the liquid test kits show 8.2/8.3 while the probe shows 7.8

So if Lou is correct then everyone using a liquid test kit has a pH much lower than actual. If that is true, then is it really so bad?

Hmmm challenging. What about dripping kalkwasser? That will increase your PH and Cal. I'm not sure how much of an affect it will have on the Alk

 

[ryshark]

Or, maybe you got a bad probe. So, if you were to take the probe out of the sump and stick it directly inside a fresh pouch of calibration solution at 7.01, is that what it would read?

 

[cmor1701d]

I use 2 part (Randy's formulas). I'm just making a batch of Ca today. Not sure I want to increase Alk any higher than it is.

The monitor does show the pH over 7.8 before lights out. They just came on an hour 45 ago, but won't reach peack for another 15 minutes (2 hour dawn/dusk gradual ramp up/down)